1. Description of the Prior Art
Hermetic refrigeration motor-compressor units conventionally include a motor driving a compressor having suction and discharge ports. A hermetically sealed casing encloses the motor and compressor and has a gas inlet opening adapted to be coupled by a conduit to the evaporator of the refrigeration system, and a discharge conduit is coupled to the compressor discharge port and extends out of the casing to the condenser of the refrigeration system. In order to achieve noise reduction, it is known to provide a suction muffler in the casing, such a muffler being shown in U.S. Pat. No. 2,133,875 and in U.S. Pat. No. 3,610,784 assigned to the assignee of the present application. It is also known to position the inlet opening of the suction muffler in spaced alignment with the inlet opening of the casing to provide a sem-direct suction coupling.
A slugging problem has been encountered in prior semi-direct suction muffler systems, i.e., under certain conditions, particularly in the case of an airconditioning system in which the compressor and evaporator are located out-of-doors, a slug of liquid refrigerant may be drawn into the suction muffler and thence into the compressor which may cause an excessive overpressure condition capable of rupturing gaskets, breaking valves, or altering the bearing alignment of the compressor.
Various slug-inhibiting arrangements have been employed in refrigeration systems including accumulators external to the compressor casing, as shown for example in U.S. Pat. Nos. 3,084,523, 3,180,567 and 3,563,053, and U.S. Pat. No. 3,387,774 discloses a slug-inhibiting system wherein a liquid refrigerant slug is rejected by the fan formed on the end ring of a compressor drive motor.
It is desirable to provide a hermetic refrigeration motor-compressor assembly including a suction muffler within the hermetically sealed compressor casing with semi-direct suction and including means for inhibiting slugs of liquid refrigerant from entering the compressor, the system also providing minimum heat-transfer to the cool gas entering the compressor thereby improving the efficiency of the refrigeration apparatus.